Abstract
Mycoplasma gallisepticum (MG) is an avian respiratory pathogen causing significant global economic losses to the poultry industries. Current live-attenuated and bacterin vaccines provide some measures of protective immunity but exhibit suboptimal efficacy, utility, or safety. To address these shortcomings, we utilized knowledge of MG biology and virulence to develop a subunit vaccine containing recombinantly produced primary adhesin GapA, cytadhesin-related molecule CrmA, and four early-phase-expressed variable lipoprotein hemagglutinins (VlhAs) (3.03, 3.06, 4.07, 5.05) of the virulent strain Rlow. The vaccine was tested in chickens using a subcutaneous dose of 50 µg per protein, a prime-boost schedule, and strain Rlow challenge in multiple studies to compare adjuvant formulations. While different adjuvants resulted in variable levels of protection, only CpG oligodeoxynucleotide (CpG ODN 2007) resulted in significant reductions of both MG recovery and tracheal pathology. These results demonstrate that a rationally designed and safe subunit vaccine is efficacious against MG disease.